Top Bush and Clinton administration officials are appearing Tuesday before a special commission investigating the September 11, 2001, terrorist attacks.

Former U.S. Secretary of State Madeleine Albright is the first high-level official to testify today. She said the Clinton administration had made al-Qaida leader Osama bin Laden a primary target and tried to kill him.

She said the United States owes it to the families of the victims to do everything it can to prevent future attacks, using all the tools at its disposal, including cooperative diplomacy with other countries.

Secretary of State Colin Powell and Defense Secretary Donald Rumsfeld are among the officials scheduled to give testimony at open hearings of the National Commission on Terrorist Attacks Upon the United States, also known as the 9/11 Commission. The commission says the hearings will focus on the conduct of U.S. counter-terrorism - particularly during the period from the August 1998 embassy bombings in Kenya and Tanzania to September 11, 2001. It is probing why U.S. intelligence failed to prevent the attacks that killed more than three thousand people.

Tuesday's testimony comes as the Bush administration is strongly rejecting accusations from former White House counter-terrorism official Richard Clarke that it ignored the al-Qaida threat in the months leading up to the attacks on the World Trade Center and the Pentagon.

In a book released Monday, Mr. Clarke says the president urged him to look for a connection between the terrorist attacks and former Iraqi leader Saddam Hussein - although he said there was no evidence such a link existed. Mr. Clarke said the president should have focused more on al-Qaida instead of Iraq.

Commission member Tim Roemer, a former Democratic congressman, mentioned the blistering accusations in the book Tuesday and called on National Security Adviser Condoleeza Rice to reconsider her decision not to testify publicly and to appear before the commission on Wednesday.

Some information for this report provided by AP, AFP and Reuters.